.\"	$OpenBSD: getgroups.2,v 1.13 2013/07/17 05:42:11 schwarze Exp $
.\"	$NetBSD: getgroups.2,v 1.8 1995/02/27 12:32:57 cgd Exp $
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.\"     @(#)getgroups.2	8.2 (Berkeley) 4/16/94
.\"
.Dd $Mdocdate: July 17 2013 $
.Dt GETGROUPS 2
.Os
.Sh NAME
.Nm getgroups
.Nd get group access list
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
.Fn getgroups "int gidsetlen" "gid_t *gidset"
.Sh DESCRIPTION
.Fn getgroups
gets the current group access list of the current user process
and stores it in the array
.Fa gidset .
The parameter
.Fa gidsetlen
indicates the number of entries that may be placed in
.Fa gidset .
.Fn getgroups
returns the actual number of groups returned in
.Fa gidset .
No more than
.Dv {NGROUPS_MAX}
will ever
be returned.
If
.Fa gidsetlen
is 0,
.Fn getgroups
returns the number of groups without modifying the
.Fa gidset
array.
.Sh RETURN VALUES
A successful call returns the number of groups in the group set.
A value of \-1 indicates that an error occurred, and the error
code is stored in the global variable
.Va errno .
.Sh ERRORS
The possible errors for
.Fn getgroups
are:
.Bl -tag -width Er
.It Bq Er EINVAL
The argument
.Fa gidsetlen
is smaller than the number of groups in the group set.
.It Bq Er EFAULT
The argument
.Fa gidset
specifies an invalid address.
.El
.Sh SEE ALSO
.Xr getgid 2 ,
.Xr setgid 2 ,
.Xr setgroups 2 ,
.Xr initgroups 3
.Sh STANDARDS
The
.Fn getgroups
function conforms to
.St -p1003.1-2008 .
.Sh HISTORY
The
.Fn getgroups
system call first appeared in
.Bx 4.1c .
